U.S. patent number 4,845,346 [Application Number 07/173,674] was granted by the patent office on 1989-07-04 for touch panel having parallax compensation and intermediate coordinate determination.
This patent grant is currently assigned to Alps Electric Co., Ltd.. Invention is credited to Kazuo Hasagawa, Junichi Ouchi, Hiroaki Sasaki.
United States Patent |
4,845,346 |
Ouchi , et al. |
July 4, 1989 |
Touch panel having parallax compensation and intermediate
coordinate determination
Abstract
Disclosed is here a coordinate input apparatus in which light
sources and light receiving elements opposing thereto with an input
operation space therebetween are arranged in an X-axis direction
and in an Y-axis direction. The light sources and said light
receiving elements form a plurality of pairs and the light sources
are sequentially driven to accomplish a scan operation. Coordinates
corresponding to the light receiving element of which a light path
is interrupted by a coordinate input scan in the input operation
space are outputtted as detection signals and as coordinate input
data of a position where the light path is interrupted. The
apparatus includes a double-precision coordinate calculate unit for
calculating, when light paths of two adjacent light receiving
elements are simultaneously interrupted, coordinates of an
intermediate point associated with coordinates corresponding to the
two light receiving elements and a coordiante value correcting unit
for achieving a parallax correction on the coordinates calculated
by the double-precision calculate unit by use of a correction
table. As an output from the coordinate correcting unit is
converted into be coordinates corresponding to the arrangement
constituted with the light sources and the light receiving elements
so as to be outputted as coordinate input data.
Inventors: |
Ouchi; Junichi (Furukawa,
JP), Sasaki; Hiroaki (Furukawa, JP),
Hasagawa; Kazuo (Furukawa, JP) |
Assignee: |
Alps Electric Co., Ltd.
(JP)
|
Family
ID: |
16006245 |
Appl.
No.: |
07/173,674 |
Filed: |
March 25, 1988 |
Foreign Application Priority Data
|
|
|
|
|
Jul 16, 1987 [JP] |
|
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62-176016 |
|
Current U.S.
Class: |
250/221; 341/31;
345/178 |
Current CPC
Class: |
G06F
3/0421 (20130101); G06F 3/0418 (20130101) |
Current International
Class: |
G06F
3/033 (20060101); G01V 009/04 () |
Field of
Search: |
;250/221
;340/712,555,556 ;341/31 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Westin; Edward P.
Assistant Examiner: Shami; Khaled
Attorney, Agent or Firm: Shoup; Guy W. Winters; Paul J.
Malaska; Stephen L.
Claims
What is claimed is:
1. A coordinate input apparatus in which light sources and light
receiving elements opposing thereto with an input operation space
therebetween are arranged in an X-axis direction and in an Y-axis
direction, said light sources and said light receiving elements
forming a plurality of pairs, said light sources are sequentially
driven to accomplish a scan operation, coordinates corresponding to
said light receiving element of which a light path is interrupted
by a coordinate input scan in said input operation space are
outputted as detection signals and as coordinate input data of a
position where the light path is interrupted comprising:
double-precision coordinate calculate means for calculating, when
light paths of two adjacent light receiving elements are
simultaneously interrupted, coordinates of an intermediate point
associated with coordinates corresponding to said two light
receiving elements and
coordinate value correct means for achieving a parallax correction
on the coordinates calculated by said double-precision calculate
means by use of a correction table wherein
an output from said coordinate correct means is restored to be
coordinates corresponding to said arrangement constituted with the
light sources and said light receiving elements so as to be
outputted as coordinate input data.
2. A coordinate input apparatus according to claim 1 wherein each
said light sources is a photoemitter.
3. A coordinate input apparatus according to claim 1 wherein each
said light receiving elements is a photosensor.
4. A coordinate input apparatus according to claim 1 wherein said
duble-precision coordinate calculate means includes change-over
switch means, detection start coordinate memory means, continuous
counter circuit means, multiplier means, and adder means.
5. A coordinate input apparatus according to claim 1 wherein said
coordinate value correct means includes correction area position
memory means, detection position comparator means, correction data
memory means, adder means, and divider means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a coordinate input apparatus in an
information processing system, and in particular, to a coordinate
input apparatus which detects a position in a two-dimensional space
so as to input the position as coordinate data, for example, in a
host computer of the information processing system.
2. Description of the Prior Art
The coordinate input apparatuses of this kind include an optical
coordinate input apparatus in which photoemitters as light sources
and photosensors as light receivers paired with the photoemitters
are arranged with an input plane (input operation space)
therebetween such that the photoemitters oppose to the photosensors
in the X and Y directions and a coordinate input apparatus of an
induced voltage method in which a great number of sense lines are
arranged in the X and Y directions with respect to the input
direction so as to form a matrix thereof, thereby sensing induced
voltages appearing in said sense lines. These coordinate input
apparatuses are generally called touch input apparatuses or touch
panels. (Incidentally, in the case of the optical coordinate input
apparatus, the input is supplied through an interruption of the
light sources and hence the operation to touch the apparatus need
not be necessarily effected.)
In the input apparatuses such as the touch panel, regardless of the
type thereof described above, an input space of a finger or a
position on the panel is detected as data associated with the X and
Y coordinates through an input operation so as to input the
coordinate data in the host computer or the like.
In the following paragraphs, description will be particularly given
of an example of an optical coordinate input apparatus.
In the optical coordinate input apparatus, as described above, the
light sources (photoemitters) and light receiving elements
(photosensors) paired therewith are arranged so as to oppose to
each other, and according to a counter value delivered from a
counter circuit, the light sources are sequenctially driven to
effect a scanning operation. In this fashion, a sense signal is
produced when a light is not received because a light path is
interrupted by a coordinate input operation, for example, through a
touch of a finger and the light from a photoemitter does not reach
the corresponding photosensor. The counter value associated with
the sense signal is detected as an input coordinate data.
The coordinate input apparatus of this kind is employed in various
manners, for example, the apparatus is mounted on a CRT face of a
CRT unit as a terminal of an information processing system so as to
effect an input operation by use of a display on the CRT face as a
target, or the apparatus is located on a sheet to effect an input
operation by tracing an image on the sheet.
Furthermore, particularly, in a case where the coordinate input
apparatus is disposed on a CRT face for the use thereof, there
appears a parallax between an image displayed as a target on the
face and a panel of the coordinate input apparatus generally made
of a flat, transparent material, which leads to a problem that
coordinate data other than desired coordinate data is inputted.
FIG. 7 is an explanatory diagram useful to explain an occurrence of
a parallax which includes a display unit (for example, a CRT) 100,
a coordinate input apparatus 200, a display surface 300 of the
display unit (for example, a face of the CRT), a display area 400,
positions of an eye 500 and 600, a display area P.sub.2 -Q.sub.2 '
on the coordinate input apparatus 200 associated with the eye
position 500, and a display area P.sub.2 '-Q.sub.2 on the
coordinate input apparatus 200 associated with the eye position
600,
In FIG. 7, when the display surface 300 of the display apparatus
100 becomes apart from the coordinate input apparatus 200,
particularly when the display surface 300 is a curved surface like
the face of a CRT, depending on the position of the eye of the
user, there appears a positional unmatching due to a parallax
between a position (coordinate point) of the coordinate input
apparatus and the display area 400 of the display apparatus. In
this figure, for the eye position 500, a display area P.sub.2
-Q.sub.2 ' results on the coordinate input apparatus 200, whereas
for the eye position 600, a display area P.sub.2 '-Q.sub.2 is
attained on the coordinate input apparatus 200.
Consequently, for the eye position 500, point P, in the display
area 400 of the display apparatus, namely, point P.sub.2 where a
line connecting between the eye position 500 and the point P.sub.1
intersects the coordinate input apparatus 200 is not attended with
a positional difference; consequently, when a coordinate input
operation is effected on the point P.sub.2 of the display apparatus
200, for example, by touching the point P.sub.2 by a finger, th
point P.sub.1 as a target in the display apparatus 100 can be
inputted as correct coordinate data in a host computer or the like.
However, when inputting the point Q.sub.1 of the display apparatus,
the input operation is effected by touching point Q.sub.2 ' of the
display apparatus, namely, point Q.sub.1 ' apart from the objective
point Q.sub.1 by a distance of D corresponds thereto, and as a
result, wrong data is inputted.
In order to prevent a wrong data input of the coordinate input
apparatus due to the parallax, there has been disclosed, for
example, a method by the Japanese Patent Laid-Open No. 62-99824 in
which a correction table is employed. According to this method,
input point coordinates indicated by an input operation and
correction values corresponding to a parallax at the input point
are stored in an ROM so as to automatically correct a wrong data
input due to the parallax of the input coordinate point.
In addition, the Japanese Patent Laid-Open No. 61-208532 discloses
a system which employs an ROM table storing the similar correction
values and which includes a hierarchic structure where
photoemitters and photosensors of a coordinate input apparatus
arranged on a display apparatus are located in the proximity of
each other on a curved surface of the face of a CRT as the display
apparatus.
However, according to the prior art technology described in the
publication above, the detection of the input point coordinates of
the coordinate input apparatus is effected in the X-Y matrix
disposed in a discrete fashion on a two-dimensional space;
consequently, the correction table stores predetermined correction
values for each group including a plurality of areas on the
two-dimensional plane of the coordinate input apparatus, which
leads to a problem that defects of coordinates occur on boundaries
where the correction values vary.
Next, referring to the drawings, the mechanism of occurrence of the
problem will be described.
FIG. 8 is an explanatory diagram useful to explain an example of a
parallax correction table, whereas FIG. 9 is an explanatory diagram
useful to explain coordinate data corrected by use of the
table.
In FIG. 8, reference numerals 0, 1, 2, etc. correspond to positions
of the photosensors and T.sub.11, T.sub.12, . . . , T.sub.21,
T.sub.22, . . . , T.sub.31, T.sub.32, etc. indicate respective
correction areas.
In this configuration, for example, in the correction area
T.sub.11, when a photosensor X-1 of the X coordinate and a
photosensor Y-1 of the Y coordinate are inputted through an input
operation (the light sources to the photosensors X-1 and Y-1 are
interrupted), the coordinates (1, 1) of the input point are
corrected as coordinate input data to be (0, 0) since the
correction values are X:-1 and Y:-1, and for the coordinates (1,
6), the correction values are X:-1 and Y:+1 and hence the
coordinate input values are corrected and are outputted as (0, 7).
Incidentally, when the value after the correction is negative (-),
0 is assumed, whereas when the value exceeds the maximum value in
the X or Y direction, the corresponding maximym value in the X or Y
direction is assumed.
The coordinate input data thus corrected in the correction
procedure are shown in FIG. 9. In this figure, the arrows indicate
the correction directions.
In FIG. 9, S.sub.11, S.sub.12, . . . , S.sub.21, S.sub.22, . . . ,
S.sub.31, S.sub.32, etc. denote coordinate input data after the
correction. As can be seen from this figure, the erroneous input
due to the parallax is corrected by the correction above. However,
at positions 2 and 7 in the X direction and at positions 2 and 5 in
the Y direction as indicated by the arrows A-D, there occur defects
of coordinate input data.
That is, for the coordinate input data, at the X coordinates 2 and
7 and at the Y coordinates 2 and 5, data are missing in any
cases.
As shown in FIGS. 8-9, in an apparatus in which the coordinate
input data is attained according to a physical arrangement of
photoemitters and photosensors (to be referred to as a
single-precision coordinate input apparatus herebelow), when an
input operation is accomplished astriding two adjacent
photosensors, for example, X=2 and X=3, the detection is effected
at either X=2 or X=3 according to the priority processing;
consequently, for X=2, since the table T.sub.11 of FIG. 8 includes
the correction value X:-1, the coordinate input data is assumed to
be X=1. On the other hand, for X=3, the correction value in the
table T.sub.12 is X:0 and hence the coordinate input value is X=3
without any alteration.
As a result, the coordinate input data for X=2 is not included as
data.
As an improvement of the single-precision coordinate input
apparatus having the priority processing, the present applicant has
already proposed in the Japanese Patent Application No. 62-62158 an
apparatus (to be referred to as a double-precision coordinate input
apparatus) in which when an input operation is effected astriding
two adjacent photosensors, the intermediate point of the two
coordinate values is calculated.
However, also in the double-precision coordinate input apparatus,
there occur defects of coordinate input data.
According to the prior art technology described above, in an
apparatus in which an error of coordinate input data caused by a
parallax of the coordinate input apparatus is corrected by use of a
correction table including a plurality of areas established in
accordance with relative positions between the coordinate input
apparatus and the display apparatus, there has been a problem that
depending on a difference between the correction values in areas of
the correction table, there occur defects of coordinate input data
on area boundaries.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a
coordinate input apparatus which removes the defects of the
coordinate input data also on boundaries of areas of the correction
table, thereby solving the problems of the prior art
technology.
The problems above can be solved as follows. Namely, coordinate
values are also set at intermediate points of the respective
photosensors, and there are disposed means (double-precision
calculate means) for calculating the coordinates of an intermediate
point when a plurality of photosensors are detected for an input as
a result of an input operation and means for correcting the
coordinate values thus calculated for the intermediate point,
thereby dividing the corrected coordinate values by two so as to
output the results as the single-precision coordinate data.
Referring now to FIGS. 5-6, a description will be given of the
principle of the present invention.
FIG. 5 is an explanatory diagram useful to explain an example of
the correction table according to the present invention in which
the digits in the parentheses indicated in the X and Y directions
are the coordinates corresponding to the single-precision data of
the conventional example of FIG. 8, whereas the digits not enclosed
in the parentheses indicate coordinates including intermediate
points established according to the double-precision
calculation.
In the figure, the correction values (in the double precision)
associated with the parallax between the display apparatus and the
coordinate input apparatus are beforehand stored in the form of the
correction table in an ROM such that a correction area T.sub.11 '
with X:-2, Y:-2, a correction area T.sub.12 ' with X:0, Y:-2, and
so forth.
FIG. 6 is an explanatory diagram useful to explain the results of
the correction achieved by use of the correction tble of FIG. 5 in
which indicates detection coordinates in the single precision,
namely, physical detection coordinates and represents
intermediate-point coordinates attained by the double-precision
computation.
In FIGS. 5-6, in the coordinate input apparatus, the operation is
achieved according to the physical configuration of detecting
devices of the coordinate input apparatus, namely, in an optical
coordinate input apparatus, the operation is effected by
interrupting at least one light beam in an input space comprising a
matrix of light beams linking photoemitters and photosensors in the
X and Y directions.
For example, when coordinates [X:(2), Y:(2)] are detected in the
correction area T.sub.11 ', the coordinates [X:(2), Y:(2)] are
corrected to be [X(1), Y(1)] according to the correction values
X:-2, Y:-2 stored in the correction table. When coordinates [X:(2),
Y:(2)] and [X:(1), Y:(2)] are simultaneously detected, coordinates
[X:3, Y:(2)] of an intermediate point therebetween are calculated
and a correction is accomplished for the coordinate point by use of
the corrsponding correction values; as a result, the coordinates
thus corrected are attained as [X:(0), Y:(1)], which are inputted
as detection coordinate data in a host computer or the like.
Silimarly, when coordinates [X:(2), Y:(3)] and [X:(3), Y:(3)] are
simultaneously detected, coordinates [X:5, Y:(2)] of an
intermediate point therebetween are calculated in the
double-precision computation. Since the coordinates are associated
with the correction values [X:0, Y:0], the values of the
coordinates are directly converted into single-precision
coordinates, which are inputted as coordinate input data in a host
computer or the like.
As described above, according to the present invention, in a case
where input detections are achieved on the adjacent photosensors,
an intermediate point therebetween is calculated by the
double-precision computation so as to effect the correction
depending on the coordinates of the intermediate point;
consequently, there are avoided the defects of the coordinate input
data appearing on boundaries of areas of the correction table in
the prior art technology.
In addition, also for the correction coordinates of the
single-precision coordinates, the correction table is established
in association with the coordinates calculated by the
double-precision computation; consequently, even when the
correction table is arbitrarily established, there does not appear
the defect in the coordinate input data on boundaries of the
correction areas, which enables the parallax taking place with
respect to the employed display apparatus to be appropriately
altered and hence the associated erroneous data input can be
prevented.
Since the correction of the parallax is accomplished with respect
to coordinates of an intermediate point obtained by the
double-precision computation, even when an input operation is
achieved on a boundary of areas of the correction table, the defect
of the coordinate data does not occur when the single-precision
data is to be outputted.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be apparent from the following detailed
description taken in conjunction with the accompanying drawings in
which:
FIG. 1 is a schematic block diagram showing an embodiment of the
coordinate input apparatus according to the present invention;
FIG. 2 is a block diagram showing in detail the comparator section
of FIG. 1;
FIG. 3 is a detailed block diagram illustrating the scan end
comparator section of FIG. 1;
FIG. 4 is a flowchart for explaining the operation of the present
invention;
FIG. 5 is an explanatory diagram useful to explain an example of
the correction table according to the present invention;
FIG. 6 is an explanatory diagram for explaining the principle of
the correction according to the present invention;
FIG. 7 is an explanatory diagram for explaining a mechanism of an
occurrence of a parllax in a coordinate input apparatus;
FIG. 8 is an explanatory diagram useful to explain an example of
the correction table in the prior art technology; and
FIG. 9 is an explanatory diagram for explaining the principle of
the correction according to the prior art technology.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, description will be given of an
embodiment according to the present invention.
FIG. 1 is a block diagram useful to explain an embodiment of the
coordinate input apparatus according to the present invention which
includes a counter 1, a pulse generator 2, a coordinate detecting
section 3, an amplifier section 4, a comparator section 5, a
change-over swich 6, a detection start coordinate memory 7, a
continuous counter circuit 8, a multiplier 9, an adder 10, a
correction area position memory 11, a detection position comparator
12, a correction data memory 13, an adder 14, a divider 15, a
non-detection code memory 16, an error code memory 17, change-over
switches 18-20, an output code memory 21, and an output control
section 22. The configuration further comprises a double-precision
coordinate computation section 200 including the switch 6, the
detection start coordinate memory 7, the continuous counter circuit
8, the multiplier 9, and the adder 10. Furthermore, the system
includes a coordinate correction section including the correction
area position memory 11, the detection position comparator 12, the
correction data memory 13, the adder 14, and the divider 15.
Next, a description will be given of the function of each block of
FIG. 1.
The counter 1 is reset by a reset signal RS and increments the
count value by one each time a signal on a signal line k is
inputted in synchronism with a clock signal CLK.
The pulse generator 2 generates pulses according to the count
output from the counter circuit 1.
The coordinate detecting section 3 effects a coordinate detection
based on the pulse from the pulse generator 2 and the counter value
from the counter circuit 1 and then outputs the result.
The amplifier 4 amplifies a signal from the coordinate detecting
section 3, shapes the waveform thereof, and outputs the resultant
signal.
The comparator 5 will be described later in conjunction with FIG.
2.
The change-over swtch 6 sends the counter value from the counter
circuit to the detection start coordinate memory 7 in response to a
signal f.
The contents of the detection start coordinate memory 7 are reset
with the reset signal RS. The memory 7 stores the counter value
from the counter 1 via the switch 6 and outputs the counter value
to the multiplier 9.
The continuous count value of the continuous counter circuit 8 is
reset with the reset signal RS. The counter circuit 8 increments
the continuous counter value in response to a signal on a signal
line g and outputs the continuous counter value to the adder
10.
The multiplier 9 multiplies the data on the signal line g by two
and outputs the resultant data.
The adder 10 adds data on signal line x to data on signal line y so
as to output the result to the detection position comparator 12 and
the adder 14.
The non-detection code memory 16 is beforehand loaded with
non-detection codes, which are to be delivered to the switch
19.
The error code memory 17 is beforehand loaded with error codes,
which are to be delivered to the switch 18.
The change-over switches 19-20 are responsive to signals from
signal lines i.sub.0 -i.sub.2 so as to output one of data signals
from the non-detection code memory 16, the error code memory 17,
and the divider 15 to the output code memory 21.
The output code memory 21 stores data from the switches 18-20 and
ouputs the data to the output controller 22.
The output controller 22 outputs data from the output code memory
21 in response to the output control signal z.
In FIG. 1, the double-precision compute section 200 and the
coordinate correct section 300 are each prepared for the X axis and
Y axis and the functions thereof are changed over depending on the
count value from the counter circuit 1.
In addition, the correction area position memory 11 is beforehand
loaded with coordinate positions where corrections are to be
effected and the correction values thereof are set to the
correction data memory 13.
Although a read-only memory (ROM) is employed for the correction
data memory 13, the memory is not limited to an ROM, namely, an ROM
(PROM, E.sup.2 PROM) in which a rewrite operation is possible may
be used; furthermore, an RAM may also be applied thereto.
The detection position comparator 12 compares the data from the
correction area position memory 11 with the data from the adder 10
so as to deliver via signal line l from the correction data memaory
13 correction data corresponding to the correction area
location.
The correction data memory 13 is responsive to a signal from the
signal line l to output the pertinent correction data.
The adder 14 adds the data from the adder 10 to the data from the
correction data memory 13 so as to output the result to the switch
20.
FIG. 2 is a detailed block diagram showing the comparator of FIG. 1
which includes a change-over switch 50, a detection
presence/absence comparator 51, a detection start flag memory 52, a
detection start comparator 53, a continuation flag memory 54, a
continuation detection comparator 55, a single counter 56, a scan
end counter value memory 57, a scan end comparator 58, and an error
non-detection comparator 59.
Next, a description will be given of each block of FIG. 2.
The detection presence/absence comparator 51 determines whether the
detection signal has been detected or not.
(i) In a case of non-detection
A signal is transmitted to a signal line to reset the continuation
flag 54.
(ii) In a case of detection
A signal is set to a signal line 51a to operate the detection start
comparator 53.
The detection start comparator 53 judges the content of the
detection start flag 52.
(i) If the detection start flag 52 has been reset (at a first
detection)
A signal is transmitted to a signal line f:
to set the detection start flag,
to set the continuation flag,
to increment the content of the single counter by one, and
to operate the switch 6 so as to send the counter value from the
counter circuit 1 to the detection start coordinate memory 7.
(ii) If the detection start flag 52 has been set (at the second and
subsequent detections)
A signal is sent to a signal line 53a to operate the continuation
detection comparator 55.
The continuation detection comparator 55 judges the content of the
continuation flag.
(i) If the continuation flag 54 has been reset (detections have
been effected at two or more positions apart from each other)
A signal is transmitted to a signal line 55a to increment the
content of the single counter 56 by one.
(i) If the continuation flag 54 has been set (detections have been
continuously effected)
A signal is transmitted to a signal line g to the continuous
counter so as to increment the content thereof by one.
Incidentally, it is assumed that the detection start flag 52 has
been reset in advance with a reset signal and that the single
counter 56 has been beforehand reset by a reset signal.
Although a description will be later given of the scan end
comparator section of FIG. 3 including the scan end counter value
memory 57 and the scan end comparator 58, the scan end comparator
section has the following functions.
That is, the scan end comparator 58 compares the content of the
scan end counter value memory 57 with the counter value so as to
judge whether or not the scan has been ended.
(i) In a case where the scan has not been terminated (counter
value<scan end counter value)
A signal is transmitted to a signal line h to operate the counter
circuit 1 so as to increment the counter value by one.
(ii) In a case where the scan has been terminated (counter
value=scan end counter value)
The error non-detection comparator 59 is caused to start its
operation.
The error non-detection comparator 59 judges the content of the
single counter value 56.
(i) In a case of single counter value=0 (detection has not been
effected)
A signal is sent to a signal line i.sub.0 to operate the switch 19
so as to send the content of the non-detection code memory 16 to
the output code memory 21.
(ii) In a case of single counter value=1 (detection has been
effected; no error)
A signal is sent to the signal line i.sub.1 to operate the switch
19 so as to send the content of the divider 15 to the output code
memory 21.
(iii) In a case of single counter value.gtoreq.2 (detections have
been effected at two or more positions apart from each other)
A signal is sent to the signal line i.sub.2 to operate the switch
19 so as to send the content of the error code memory 17 to the
output code memory 21.
Incidentally, the content of the scan end counter value memory has
been set in advance.
FIG. 3 is a detailed block diagram showing the scan end comparator
section which includes an X-axis scan end counter value memory 571,
a scan end counter value memory 572, an X-axis scan end compartor
581, and a scan end comparator 582.
In this figure, the X-axis scan end comparator 581 sends a signal
to the signal line h when the content of the counter value is less
than the content of the X-axis scan end counter value memory 571;
otherwise, a signal is sent to the signal line h.sub.1 to operate
the scan end comparator 582 and to cause the switch 50 (FIG. 2) to
change over the destination of the counter value from the X-axis
block to the Y-axis block.
The scan end comparator 582 sends a signal to the signal line h
when the content of the counter value is less than the content of
the scan end counter value memory 572. When the contents become to
be equal (the scan is finished on the X ans Y axes), a signal is
sent to the signal line 7 so as to output from the error
non-detection comparator 59 (for the X and Y axes) the signal
i.sub.0, i.sub.1, or i.sub.2 corresponding to the value of the
single counter 56 (FIG. 2).
FIG. 4 is a flowchart useful to explain the operation of the
coordinate input apparatus according to the present invention.
In FIG. 4, according to the result of the scan of step 1, it is
judged whether or not an input detection has been accomplished
(step 2). When the detection has been effected, it is judged
whether or not an error results (step 3). For a normal input
detection, the coordinate position is computed in the double
precision (step 4). The double-precision calculation is achieved by
the double-precision compute section 200 of FIG. 2.
The coordinate values thus attained by the double-precision
computation are processed in the coordinate value correction
section 300 of FIG. 1 such that correction data corresponding to
the correction area of the correction area position memaory 11 is
read from the correction data memory 13 and that the detected
coordinate values are added to the coordinate values above in the
adder 14, thereby achieving the correction associated with the
parallax (step 5). The principle of the correction is identical to
that described in conjunction with FIGS. 5-6.
The coordinate values thus corrected are divided by two by the
divider 15 of FIG. 1 so as to be converted into coordinate values
in the single precision (step 6). The conversion of the coordinate
values into the single-precision values is executed, as shown in
FIG., 6 such that the double-precision coordinate values 0-1, 2-3,
4-5, 6-7, etc. are respectively related to the single-precision
coordinate value (0), (1), (2), (3), etc.
The coordinate values thus obtained in the single precision are
delivered as coordinate input data via the output code memory 21
and the output controller 22, as shown in FIG. 1, to a host
computer or the like (step 7).
On the other hand, when the input detection is missing in the step
2, a non-detection code is outputted from the non-detection code
memory 16 of FIG. 1 (step 9).
Furthermore, when an error input is found in the step 3, an error
code is delivered from the error code memory 17 of FIG. 1 (step
8).
Through the operations above, the double-precision computation is
accomplished for the input coordinate position detected so as to
calculate the coordinates of the intermediate point, a correction
is achieved on the resultant data with the correction values set to
the correction table, and then the obtained values are converted
again into single-precision values, thereby avoiding the defects of
the coordinate data in the physical coordinate values.
As described above, according to the present invention, the defects
of the input data occurring on boundaries of areas when the
parallax correction values are set for the respective areas
corresponding to the positions between the display apparaus and the
coordinate input apparatus, which consequently removes the drawback
of the prior art technology and provides a coordinate input
apparatus having an efficient performance.
While the present invention has been described with reference to
the particular illustrative embodiments, it is not restricted by
those embodiments but only by the appended claims. It is to be
appreciated that those skilled in the art can change and modify the
embodiments without departing from the scope and spirit of the
present invention.
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